This invention relates to precision machinery components formed by using a special thermosetting resin composition.
Precision machinery components which require high dimensional accuracy and dimensional stability have been made of metal in most cases. But in order to conduct precision working of metals, various apparatuses and high techniques for cutting and surface finishing are necessary. Further, in the working of parts having complicated forms, complicated working procedures and long working time are necessary, which results in making the production cost high.
Thus, in order to remove such defects mentioned above as well as for weight saving, various machinery components have recently been made of plastics. For example, electrical parts, automotive parts, and various parts of machines and instruments are made of various thermosetting resins such as phenolic resins, melamine resin, urea resin, epoxy resins, unsaturated polyester resins, silicone resin, polyimide resins, and the like, or of various thermoplastic resins such as polyethylene, polystyrene, polyvinyl chloride, polymetharylates, nylons, polycarbonates, polyphenylene oxide, polyphenylene sulfide, polyethylene terephthalate, polybutylene terephthalate, and the like, or of those filled with inorganic fillers or those reinforced with fibrous reinforcing materials. Since the resinous materials mentioned above can easily be formed into the desired shapes by using injection or transfer molding machines, the processing cost is very cheap.
But since shaped articles made of various plastics mentioned above are inferior to those made of metals in mechanical strength, thermal conductivity, electrical conductivity, dimensional accuracy, durability, and the like, utility of them is very limited. For example, a cylinder used in the magnetic tape scanning apparatus of a video tape recorder requires remarkably high dimensional accuracy and dimensional stability, so that it is generally made of metal such as aluminumsilicon alloy and it has been believed that such a cylinder which requires high dimensional accuracy and dimensional stability can hardly be made of plastics, since roundness of the cylinder would be changed greatly with the lapse of time under heating conditions.
None the less, precision machinery components made of plastics, particularly thermosetting resins, have been demanded from the viewpoint of weight saving and reduction in production cost.